It seems ever more certain Apple will introduce a low-cost iPhone in the next few months and that the phone will have a polycarbonate case in multiple colors. Leaked parts and photos of parts have earlier suggested brightly colored phones. The most recent photos to appear online show more muted colors. Also, these photos show a blue phone for the first time. What's going on here? Apple has likely requested the manufacturer produce back panels in various colors so it could decide which ones to go with. I personally prefer the more subdued tones shown in these photos than the previous colors.
Of course, we don't yet know anything for sure, but when these sorts of images begin appearing during the rumor cycle, it's usually a harbinger of an announcement. While there's not yet any clue to pricing, or even whether it will be available in all markets, it does see, likely the phone is indeed coming. So far, the specs suggest it'll mostly have the same form factor as the current iPhone 5 but may be just slightly thicker and taller. It's expensive to engineer a svelte phone like the iPhone 5, so it makes sense that a lower-cost iPhone wouldn't be as thin.
Many are expecting this new phone and a supposed iPhone 5S to be launched in September. There are reports that Apple's manufacturer, Foxconn, is in the midst of a massive hiring campaign, suggesting that it is gearing up for new iPhones. You can read more on AppleInsider. The timing seems about right for a September launch.